Wireless communication systems have typically selected like transmission processes for both upstream and downstream carrier signals. In these systems, therefore, a single selection is chosen as a trade-off between cost and effectiveness and such trade-offs have not generally realized optimum utilizations of existing communication technologies.
The present invention is directed to wireless communication methods and structures that enhance communication robustness while reducing cost. These goals are realized by communicating downstream data with orthogonal frequency division multiplexing (OFDM) transmission processes and upstream data with single carrier transmission processes.
This combination of transmission processes is configured with various signal modulations (e.g., quadrature phase shift keying (QPSK), m-ary phase shift keying (MPSK) and n-quadrature amplitude modulation (QAM)) to provide lower cost upstream communication from customer services equipments (CPEs) and more robust downstream communication from headends than has been achieved in conventional communication systems.
In system embodiments, signal diversity is enhanced by receiving communication signals with multiple antennas that are spatially separated and potentially have different polarizations to thereby enhance signal diversity. Signal diversity is further enhanced by combining the received signals in ways that maximize the ratio of desired to undesired signals.
The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings